1. Field of the Invention
This invention relates to an improved combustion chamber for burning a variety of fuels, and more particularly to a combustion chamber and burner configuration in which liquid fuels are mixed with air, delivered to a burner, and combusted to achieve optimum combustion at a temperature which is not deleterious to the material of the associated downstream cooking hardware.
2. Description of the Prior Art
Conventional combustion chamber and burner apparatus with which the present invention is concerned, shown generally in FIGS. 1 and 2, typically comprise an outer chamber 10 surrounding an inner chamber 12. Combustion of fuel and air mixtures take place within the inner chamber. Air from an external source is supplied to a conduit 13 at one "input" end of the outer chamber, and is caused to flow (eg., by a fan or other air mover device) through the inner chamber 12 and also through the space defined between the exterior surface of the inner chamber 12 and the interior surface of the outer chamber 10. The air which passes over the inner chamber 12 tends to cool the outer walls of inner chamber 12. When this cooling air reaches the output end (the rightmost end of the apparatus shown in FIG. 1) of the outer chamber 10 it is directed through the space defined between the concentric cylindrical exhaust sections 16 and 17.
Combustion chamber configurations of the type shown in FIGS. 1 and 2 are typically characterized by the inner chamber being of rectangular or polygonal cross-section along substantially its entire longitudinal extent, and at least one transition region 14 connecting the inner chamber with cylindrical exhaust section 17 as shown in FIG. 1. Through such transition regions 14, the inner combustion chamber is transformed from the region of rectangular or polygonal cross-section, in which combustion takes place, to the exhaust section of circular cross-section, where the products of combustion gases are to be mixed with cooling air.
One of the major difficulties with configurations of this type has been that the inner chamber must extend over a significant longitudinal extent, and oftentimes elaborate transitions are required between various inner chamber portions to convert the substantially rectangular or polygonal cross-section of the inner chamber to the circular cross-section at the exhaust section of the outer chamber.
Another problem with conventional combustion chamber configurations has been that the flame produced at the burner head takes on a long laminar shape. As a result, the flame cannot be properly or stably contained in relatively compact inner combustion chambers. Various solutions have been proposed to remedy this problem. For example, U.S. Pat. No. 4,437,831 to Brooker et al. teaches a burner head configuration for bushing out or spreading a flame. On the other hand, U.S. Pat. No. 4,094,625 to Wang et al., U.S. Pat. No. 4,023.921 to Anson, U.S. Pat. No. 3,923,251 to Flournoy and U.S. Pat. No. 3,836,315 to Shular teach shaping the flame head by introducing shaping air currents into the inner chamber at or proximal to the burner. Alternatively, U.S. Pat. No. 4,575,332 to Oppenberg et al. discloses a method of improved burning with nitrous oxide reduction involving the introduction of shaping air currents along the longitudinal extent of the inner chamber. In some applications, it has been found advantageous to provide the inner chamber with a substantial length to control the flame pattern and to accommodate the length of the flame which has been known, at times, to project up to four feet from the burner in the inner chamber even through the transition regions. Each chamber must be tailor-made for each application. This aspect of the conventional configurations is equally undesirable insofar as the heat from this extended flame pattern tends to structurally weaken, and thus significantly shorten the life of the constituent structural members.